Voltage conversion device and computer-readable recording medium having program recorded thereon for computer to control voltage conversion

1. A voltage conversion device converting a DC voltage from a DC power supply into an output voltage in such a manner that said output voltage is equal to a first target voltage, comprising: a voltage converter changing a voltage level of said DC voltage to output said output voltage; detection means detecting said output voltage output from said voltage converter; and control means conducting feedback control of said voltage converter in the manner that said output voltage is equal to said first target voltage, said feedback control conducted, in a case where a first deviation between said first target voltage and said detected output voltage is larger than a predetermined value, by changing a second target voltage of said voltage converter in such a manner that a second deviation between said second target voltage and said output voltage decreases, wherein said control means controls said voltage converter, in a case where said detected output voltage decreases below said first target voltage, so that said output voltage is equal to said first target voltage by conducting first feedback control and second feedback control, said first feedback control refers to feedback control of said voltage converter executed by changing said second target voltage in such a manner that said second deviation is at most said predetermined value, and said second feedback control refers to feedback control of said voltage converter executed, in a case where said detected output voltage having been decreasing starts to increase, by changing said second target voltage in such a manner that the rate of change of said second target voltage is at most a standard value.

2. The voltage conversion device according to claim 1 , wherein in the case where said first deviation is larger than said predetermined value, said control means conducts said first feedback control using said second target voltage determined by adding said predetermined value to said detected output voltage.

3. The voltage conversion device according to claim 1 , wherein said output voltage is input to an inverter driving an AC motor.

4. The voltage conversion device according to claim 3 , wherein said AC motor is a motor for a vehicle.

5. A computer-readable recording medium having a program recorded thereon for a computer to control voltage conversion from a DC voltage from a DC power supply into an output voltage in such a manner that said output voltage is equal to a first target voltage, said computer executing: a first step of detecting said output voltage; and a second step of conducting feedback control of a voltage converter converting said DC voltage into said output voltage, said feedback control conducted, in a case where a first deviation between said first target voltage and said detected output voltage is larger than a predetermined value, by changing a second target voltage of said voltage converter in such a manner that a second deviation between said second target voltage and said output voltage decreases, wherein said second step includes: a first sub-step of calculating said first deviation; a second sub-step of detecting that said first deviation is larger than said predetermined value; a third sub-step of conducting feedback control of said voltage converter by changing said second target voltage in such a manner that said second deviation is at most said predetermined value; and a fourth sub-step of conducting feedback control of said voltage converter, in a case where said detected output voltage having been decreasing starts to increase, by changing said second target voltage in such a manner that the rate of change of said second target voltage is at most a standard value.

6. The computer-readable recording medium according to claim 5 , wherein said third sub-step includes the steps of: calculating said second target voltage by adding said predetermined value to said detected output voltage; and conducting feedback control of said voltage converter using said calculated second target voltage.

7. The computer-readable recording medium according to claim 5 , wherein said fourth sub-step includes the steps of: detecting that said output voltage having been decreasing starts to increase; calculating a difference between a third target voltage at a first control timing and a fourth target voltage at a second control timing preceding said first control timing; comparing said difference with said standard value; calculating said third target voltage, in a case where said difference is larger than said standard value, by adding said standard value to said fourth target voltage; calculating said third target voltage, in a case where said difference is at most said standard value, by adding said predetermined value to said detected output voltage; and conducting feedback control of said voltage converter using said calculated third target voltage.

8. The voltage conversion device according to claim 2 , wherein said output voltage is input to an inverter driving an AC motor.

9. The computer-readable recording medium according to claim 6 , wherein said fourth sub-step includes the steps of: detecting that said output voltage having been decreasing starts to increase; calculating a difference between a third target voltage at a first control timing and a fourth target voltage at a second control timing preceding said first control timing; comparing said difference with said standard value; calculating said third target voltage, in a case where said difference is larger than said standard value, by adding said standard value to said fourth target voltage; calculating said third target voltage, in a case where said difference is at most said standard value, by adding said predetermined value to said detected output voltage; and conducting feedback control of said voltage converter using said calculated third target voltage.